CRISPR Updates: Breakthroughs in Genome Editing
The Evolution of CRISPR Technology
CRISPR gene editing began with the discovery of CRISPR-Cas9, a programmable system adapted from bacterial defense mechanisms. Over the years, researchers have expanded the toolbox to include Cas12a, base editors, and prime editors, each designed to increase precision, reduce off-target effects, and expand the possibilities of DNA and RNA manipulation. These innovations are no longer just laboratory curiosities but the foundation of modern genome engineering.
1987: CRISPR repeats were observed in bacterial genomes. The authors concluded, “no sequence homologous to these has been found elsewhere in procaryotes, and the biological significance of these sequences is not known.” Ishino et al. J. Bacteriology (1987)
2002: The term CRISPR was coined to describe the repetitive repeats observed in bacterial and archaeal genomes. Genes usually found associated with the CRISPR repeats were identified and named CRISPR Associated Proteins or Cas. Jansen et al. Mol. Microbiology. (2002)
2005: CRISPR spacer sequences were matched to foreign DNA. Bolotin et al. Microbiology (2005)
2006: CRISPR was first proposed to be a bacterial adaptive immune system. Makarova et al. Biol Direct (2006)
2007: CRISPR loci were found to impart phage resistance in bacteria. It was determined that CRISPR sequences together with the Cas genes impart resistance and that resistance to specific phages was determined by the spacer sequences found between CRISPR repeats. Barrangou et al. Science. (2007)
2009: RNA guided RNA cleavage is first described. Hale et al. RNA (2008)
2010: The CRISPR/Cas system was identified as a bacterial and archeal immune system that targets and cleaves phage DNA. This system was found to be dependent on the bacteria containing CRISPR spacer sequences that match the phage DNA. Additionally researchers discovered that new spacer sequences could be inserted into the bacterial/archeal chromosome making the CRISPR/Cas system an adaptive immune system. Garneau et al. Nature.
2011: Cas9 from Streptococcus pyogenes was found to associate with two RNA molecules coined crRNA and tracrRNA and that all these components are required for protection against phage infection. Deltcheva et al. Nature (2011)
2012: Cas9 was found to be an endonuclease capable of introducing DSB in DNA and that this process is dependent on complementary binding of the crRNA to the target DNA. Two nuclease domains were found in Cas9 with the HNH domain cleaving the complementary strand and the RuvC-like domain cutting the non-complementary strand. Jinek et al. Science (2012)
2013: The CRISPR/Cas9 system was used to edit targeted genes in both human and mouse cells using designed crRNA sequences. Cong et al. Science (2013)
First use in plants. Li et al. Nat Biotechnol (2013)
Also first use in plants ? Nekrasov et al. Nat Biotechnol (2013).
2014: The crystal structure of Cas9 complexed with both gRNA and targeted DNA was elucidated. Nishimasu et al. Cell (2014)
PAMs are identified as a key component of DNA target integration. Anders et al. Nature (2014).
sgRNA and Cas9 are directly delivered into cells without the use of a vector intermediate. Ramakrishna et al. Genome Res (2014)
2015: The CRISPR/Cas9 system was used to edit tri-chromosomal pre-implantation human embryos. Researchers attempted to repair the HBB locus that when mutated results in β-thalassemia blood disorders. The researchers were unable to effectively repair the mutated locus and many off target cleavages were observed. Liang et al. Protein and Cell (2015)
First use of CRISPR to edit human embryos. Liang et al. Protein Cell (2015)
The Patent Battle: Who is involved and how we got here
With the patent office’s announcement that UC-Berkeley’s and the Broad Institute’s patents do not interfere, the patent saga has reached a possible conclusion. The complicated interference proceeding resulted from multiple researchers spread across the world publishing about the CRISPR/Cas system at relatively the same time along with the creation of multiple companies to investigate the systems usefulness in medicine and agriculture. This article, published prior to the patents office decision in Science Magazine, breaks down the events leading up to the interference proceeding and how the lines were drawn.
George Church wants to use the Woolly Mammoth to combat climate change
Harvard professor George Church is attempting to use CRISPR/Cas technology to resurrect the woolly mammoth by modifying the Asian elephant. Church believes that by having cold-resistant elephants or mammoths living in the tundra, the animals will punch down the snow allowing cold air to come in and freeze the snow pack. In the summertime they would knock down trees allowing the grasses to grow thus preventing the release of carbon from the tundra
Rapid Detection and Quantification of CRISPR Induced Mutations
Detection of CRISPR mutations and the determination of mutation zygosity often slows gene editing workflows to a crawl. In this Biotechniques report, Luttgeharm et. al. describe an optimized T7 Endonuclease I heteroduplex cleavage assay that detects a wide variety of mutations and predicts mutation zygosity for individual diploid cell lines and organisms.
Scientists Breed Pigs Resistant to a Devastating Infection Using CRISPR
Porcine reproductive and respiratory syndrome virus (PRRSV)is a detrimental infection that affects pigs across the United States, estimated to cost swine producers $600 million annually. Researchers at the University of Missouri developing pigs resistant to PRRSV via the use of CRISPR/Cas9 technology . Upon exposure to PRRSV, normal pigs develop symptoms in 5 days. However, pigs engineered for resistance to the virus did not develop symptoms, and most importantly they did not produce PRRSV antibodies, indicating that the virus was unable to infect the modified pigs.
The clinical success of CRISPR in 2025 redefines the boundaries of biotechnology transforming gene editing from a laboratory experiment into a therapeutic revolution
Can CRISPR-Cas9 gene drives curb malaria?
Gene drives use selfish genes that spread through a population regardless of its ability to confer individual fitness. Multiple researchers have proposed using gene drives to control the spread of vector-borne disorders, such as malaria. Carried by certain species of mosquitos, malaria is one of the most dangerous human pathogens, gene drives could control or eliminate malaria by modifying mosquitoes to be resistant to malaria or by elimination of mosquito fertility. This opinion article highlights how CRISPR/Cas9 gene drives would work in theory as well as a discussion on the technological and ethical problems facing gene drives.
CRISPR has moved from the promise of possibility to the proof of reality 2025 marks the year humanity began rewriting disorder itself, one precise edit at a time
National Academy of Science advises caution when using CRISPR in the human germline
A panel convened by the National Academy of Sciences has released a report on the potential uses of CRISPR/Cas technology in humans. The panel strongly condemned the use of CRISPR/Cas technology for cosmetic enhancement, but embraced CRISPR use for basic research and somatic genome editing for treatment of disease. The panel did recommend caution, but left the door open to germline editing for the treatment of disease only if there is significant oversight and the disease is not treatable by conventional means.
Could Genetically Engineered Insects Squash Mosquito-Borne Disease?
Science Friday host Ira Flatow discusses CRISPR/Cas9 and gene drives and the ethical considerations for their use. Kevin Esvelt, an evolutionary engineer at MIT, and Anthony James, a researcher at the University of California contributed to the discussion.